Fuzzy-based variable impedance control of uncertain robot manipulator in flexible environment: A nonlinear force contact model-based approach

Abstract In this paper, a variable impedance control method is proposed for uncertain robotic systems based on a nonlinear force contact-based flexible environmental model. First, a nonlinear force contact model between the rigid manipulator and flexible environment is established to approximate more realistic interaction responses and to avoid excessive overshoot of the force that usually exists in the traditional spring-damping environmental model. Then, according to the force contact-based environmental model, a fuzzy-based adaptive variable impedance controller is designed to achieve position and force tracking of the manipulator, where the impedance parameters are adjusted online through the force and position feedback of the robotic system, and the fuzzy logic system $(FLS)$ is used to compensate the uncertainties. The stability of adaptive variable impedance control is proved by Routh stability criterion and the boundness of all signals in the robotic system is proved by Lyapunov stability analysis. Finally, the effectiveness of the proposed method is verified by the simulation of a two-link manipulator.